Solar urticaria is characterized by itching weals that occur a few minutes after exposure to visible or ultraviolet light. The symptoms may sometimes restrict normal daily life. Treatment is difficult in more severe cases. We describe one patient with solar urticaria who was successfully treated with cyclosporin A. The patient had first been treated with antihistamine, PUVA and chloroquine phosphate without effect. Cyclosporin was given in a dose of 4.5 mg/kg body weight/day. Phototesting before, during and after treatment showed a decreased light sensitivity to UVA, UVB and visible light during cyclosporin treatment compared with phototesting before therapy. The patient could be out in the sun for at least 1 h with minimal urticaria during cyclosporin therapy compared with only a few minutes previously. However, 1-2 weeks after cyclosporin therapy was discontinued, skin symptoms returned. Cyclosporin therapy is a possible treatment in severe cases of solar urticaria where other treatments have failed, especially in countries where treatment is necessary only for a few months during summer.